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Why are there no "sleeper" planes?
On a recent long-haul flight I sat by the windows and was dreaming away staring into infinity out of the window. Then a thought came up, in Asia sleeping busses are very common. This made me think, why are there no dedicated sleeper planes? Especially for the long-haul 10 to 13 hours this would be ideal.

Related: https://travel.stackexchange.com/questions/21713/why-are-there-no-2-3-4-5-tier-bunk-beds-on-airplanes

I watched a video of Emirates first class an it got individual cabins with beds. (There's also a bathroom with showers for those can pay US$ 10k for a good ride)

Well, the DC-3 started as the sleeper version of the DC-2. So there were sleeper planes, but the space requirement for beds made them uneconomical (except in first class).

Short answer: Money. Singapore Air tried to run an all Business Class A340 between JFK (or maybe EWR) and SIN; they could not operate profitably. I expect the same to be true even with the A350/787/777-300ER in terms of running a business class/lay flat config for long hauls.

@user1008090 BA runs an all business class service from London to JFK

@MJeffryes Indeed, but they run it on Airbus A318s, the smallest aircraft in their fleet. They're configured to carry just 32 passengers, indicating that it's a very specialist service.

@DavidRicherby True. There are some airlines that do it with a 757, though. Singapore used to have an all-business A340 that did non-stop Singapore-New York flights (which was the longest flight in the world at the time,) but they've discontinued that service. They are resuming non-stop service to New York soon, but with a normal multi-cabin configuration.

For myself, I don't see how anyone can be expected to sleep comfortably in such close proximity to a bunch of strangers.

@jamesqf It's a lot more comfortable (and much less close proximity) than trying to sleep in a 3-4-3 economy configuration...

@reirab: But I don't see how anyone could possibly sleep in economy.

"...in Asia sleeping busses are very common." Not only there. Also in South America and many other areas. In sleeping trains also exist.

"...why are there no dedicated sleeper planes?" Some people might not want to/cannot sleep on a plane. Maybe just normal places with dedicated sleeper areas.

At first, I thought this might be a question about the equivalent of "sleeper cars" (souped-up cars that look very unassuming on the outside).

In most jurisdications a large aircraft must be able to be evacuated in 90 seconds or less. Doing that in a full sleeping configuration would be difficult.

Does this kind of question not belong in Travel.SE?

I don't know, but if they did Jennifer Aniston would be doing the commercials for it.

Because "welcome to capitalism, my friend!"

British Airways actually fly a “sleeper” service between LCY and JFK.  The Airbus A318-112s that serve this route have been configured with only 32 passenger seats, all that convert to fully flat beds.  Due to takeoff weight limits at LCY (because of short runway and steep climb), the westbound service actually stops at SNN to refuel, but passengers clear US immigration there, in order to land domestic at JFK (pretty much makes up for all the time lost to refuelling); eastbound the flight is direct. https://www.britishairways.com/en-gb/information/travel-classes/business/club-world-london-city

They just don't really fly them any more.
All things considered history has a big impact on this. 13 hours is by comparison fairly short when it comes to long distance flying, historically speaking. Early aircraft that flew much slower than today's jets were built more like trains than the modern planes we have now. They had dining areas, berths, saloons, and powder rooms.
The Hindenburg had cabins for pretty much everyone aboard:

(source)
The Boeing Clipper had sizable sleeping berths that could accommodate many of the people aboard.

One of the big modern roadblocks on berths is the seatbelt regulations that accompany many modern regulating authorities. Classic berths would more than likely not pass modern safety regulations and certification tests.

"One of the big modern roadblocks on berths is the seatbelt regulations" Only partially related, but what about crew rest areas then? Are those not covered by seatbelt regulations?

Those berths have some awkward belts in them which could be implemented in regular passenger berths as they are now on some of the larger planes like the A380 etc. What we will never get back is the full size beds that we had on old dirigibles!

@MichaelKjörling You still have enough seats for the crew, AFAIK

@yo' Hopefully :) But if some of the crew is resting in the rest area, their seats may be some distance away... I actually might ask a separate question about this later.

@MichaelKjörling The crew isn't sleeping in their bunks during critical flight phases. They're required to be in a seat buckled up just like everyone else. They only occupy those bunks during cruise.

@reirab Good enough for me.

@Dave They have full size beds! In fact, these look much more luxurious than the ones on say the Hindenburg.

@Dave Two words: Singapore Suites. And, of course, there's also Etihad's The Residence if you want your own in-flight shower, butler, and living room in addition to full-size bed... and have $30k lying around for a one-way flight.

The middle illustration shows how far engine technology has developed - I did not know that they used to turn the propellers by hand during flight!

I am aware of the various full size bed options on the long haul A380's out there however those are only in part of the plane. This answer focuses on true sleeper planes where there is enough bedding to go around.

Re the Hindenburg: The Hindenburg was ****ing huge compared to modern airplanes, as is clearly visible in your image.  But it wasn't just the Hindenburg, of course.  All lighter-than-air vessels benefit from being massive via the square-cube law.  When you switch to heavier-than-air, suddenly it starts working the other way round and the cabin is abruptly tiny.

@MichaelKjörling The regulations mean you need a seat + belt for everyone on board (off-topic: exceptions apply). So you can't have beds instead of seats, but you certainly can  have beds in addition to seats - if you can afford to .

Wow that Clipper is when people who could travel really travelled in style.  Fab.

There certainly are; it's called "Business Class" and you'll find such areas with seats that recline into what are essentially beds on most long-haul aircraft. However, you simply can't fit as many people on board when they use up so much room, so airlines have to charge much more for these to make it economically viable. It's often twice the price of a normal ticket or even more.

Yeah I was exactly sitting there but it is space wise very inefficient while an Asian sleeper bus is very efficient configured with seats overlapping under and over

@Brilsmurfffje Good luck evacuating everyone from a widebody full of bunk beds in under 90 seconds.

@Brilsmurfffje if passengers got more space means there are less passengers to be evacuated

@Brilsmurfffje Unfortunately more space doesn't put more money in the airline's pockets. They're worried about fuel efficiency, and packing as many paying customers inside as possible.

@MJeffryes That's a very important point! This is not about volume of the seat/bed, but about safety standards. If these did not exist, RyanAir would really look like this: https://c1.staticflickr.com/1/23/28043469_e21fcfd265_z.jpg?zz=1

@Cooper I don't thinh airlines are worried to pack as many paying customers in a plane as possible. They want to get as much money from a flight as possible. If there would be enough 1st class customers to regularly pay the flight + profit, they won't bother with such nuissance as bussiness and economy class customers whatsoever,

I flew on one of those once... Was comfortable for maybe an hour, but fully-reclines is a bit of an exaggeration, it is nowhere near "flat". After 7 hours "across the pond" is grew to be rather uncomfortable, especially on the legs. The "aroma" in that cabin by the morning was also a little.. ripe. Not sure I'd fork over the extra for that again.

@Trevor_G Most airlines' business-class seats actually do fold into fully-flat beds these days. British Airways has a notoriously crappy business-class product. There are some airlines that still use "angle-flat" seats in business, but these are thankfully becoming fewer and farther between.

@yo' Standing seats are on the horizon.

@yo': I thought RyanAir did look like that.

The question is not "why are there no beds". It is "why are there no sleepers" like this this sleeper train. Why are there no bunk-beds? Or like this sleeper airplane?

@MJeffryes If the answer is about safety and evacuation, then that should be posted as an answer, rather than claim something about business class or whatnot. The question asks about the equivalent of sleeper buses, which are not more expensive (or pack significantly fewer people) than buses with seats. Frankly I think this exact question has been asked, and has much better answers, here

Problem with the Lufthansa concept is that if you choose it, you’re basically choosing to not be able to sit at all for the entire flight.  And the majority (even of those who do want to sleep all the way) don’t want the upper bunk.

@A.I.Breveleri not yet, but the CEO did claim they were looking into adopting standing seats.

"...you simply can't fit as many people on board when they use up so much room..." The people should use exactly the same room (=volume), sleeping or awake. This argument could maybe get refined a bit.

Twice? It's nearly 10 times the cost (about $10K) to fly business class across the pacific compared with ecconomy (about $1K).

That is not true. You can fit the same amount of people in superposed bunks. I'm not sure if it will pass security tests, though.

@Rolf Current seating is very space-efficient, with each passenger's legroom tucked beneath the seat in front. To make the same savings with horizontal bunks you'd need them stacked so close together that passengers wouldn't be able to sit upright on their own beds. That's already a problem for any elderly or less mobile passengers, not to mention the ladders they'd need to ascend to get up there!

@Cooper true that. I was thinking that it would be space efficient to have small "coffin-like" pods for sleeping, but I didn't think it as thoroughly as you did. It would indeed be challenging to get in and out of such an area. That would not work, considering safety constraints.

I have flown in sleeper class with British Airways flying overnight from Toronto to LHR.

It was an expensive luxury which started out great, but when fully reclined the bed is not exactly flat and, if you sleep on your side, there are definite pressure points on the hips and knees. That made it rather uncomfortable after a few hours. Rather than arriving refreshed and awake like I had imagined, I arrived sore, even more tired, and just a bit cranky about the waste of $$$.
The morning "aroma" in that cabin was also a bit ripe. Apparently nocturnal flatulence was not something the designers considered.
Personally, I would not fork over the extra for that again. I was much more comfortable on the return journey in an extra-wide business-class seat.
At the very least you should check to see what sleeping equipment they install. Based on the images on-line, some are apparently a lot better than others.

Thank you for making me feel much better about not being able to fly in business class.

I have to say, I fly Business on any long haul flight, and my experience is totally different to yours - I arrive refreshed, awake and relaxed.  My British Airways seat was also completely flat on all flights I have had with them (both 747 and A380).

I know that Lufthansa has this:
http://crankyflier.com/2011/03/17/lufthansa-goes-back-in-time-gives-first-class-travelers-a-seat-and-a-bed/
I have flown a fair bit in J but these lay flat seats are not the same as a mattress, some airlines provide you with one on request if they make the bed for you. My question was more related to sleeping for the masses.

@Moo yes if you fly often enough I am sure you get used to it. On a sample of one, it was like trying to sleep in a (VERY) strange bed. If you moved wrong the foot part also went down, but that may have been a fault with the one I was in.

@Brilsmurfffje yes that looks more comfortable. Re:For the masses, I don't really have comment on that, other than the shorter flight durations with modern aircraft. A dormitory type aircraft would be great for night flights, but what do you do with it for the return day-flight.

@Brilsmurfffje Lufthansa doesn't have those beds anymore (they were removed 2 or 3 years ago from the 747-400, when they removed First class completely on those planes).

Hey, Trevor, a colleague, a few days ago, had a similar unsatisfactory experience with this particular flight (on the way to southern Africa). High expectations were definitely not met.

@LightnessRacesinOrbit Yes, and they sometimes only serve regular champagne, not Dom Perignon ... so let's all stick with Economy ;)

Is LHR Lahore, or Heathrow airport (LHR)

@Qasim London : Heathrow

Not only is it expensive, as in less seats, the relatively high speed of current airliners mean that most flights aren't that long.
It wasn't always that way. In the 1930's, the average speed of an airliner was 130-180mph. Due to the slow speed and lengthy flight times, sleeping berths were installed, especially in the case of the very long range ocean transports like the Shorts Empire, Boeing 314, and Martin M130 who could remain in the air for over 24 hours. At that time, airlines still derived most of their profit from mail delivery, and there weren't that many people who would use air travel (considered dangerous and uncomfortable), so the sleeper berths were a way to encourage people to use air travel, while there weren't enough passengers to fill conventional seats on those long flights.
One land transport that had a long range was the Douglas DC2, originally developed to compete with the Boeing 247, when Boeing would only sell the 247 to United Air Lines (which it owned). American Airlines requested that Douglas develop a version of this that had sleeping berths for transcontinental flights. Douglas widened the fuselage, lengthened the wings, and called the result the Douglas Sleeper Transport.
We know this legendary aircraft, the first that could turn a profit on passenger traffic alone, by it's later name... the DC3.

"...the relatively high speed of current airliners mean that most flights aren't that long...." Probably the question asker would be happy if only the long distance flights which take more than 8 hours would be equipped with beds. There are quite a lot of them.

There are, in some business and first class seating, but it's pricey. Intercontinental flights are the only ones that extend beyond a few hours, and international flights are a small percentage of overall flights. In 1935, a flight across the US could take 16-20 hours. Today, it's more like 3-4 hours. We don't see many sleeper berths on aircraft today because the flying time is much shorter than it once was. Time waiting to take off, on the other hand...

"... international flights are a small percentage of overall flights." That's true if measured in number of flights although the more relevant number might be revenue share where international flights with larger distances flown and higher number of passengers per flight might catch up a bit.

The DC2 can fly for 6.3 hours non-stop and the DC-3 for 7.4 hours, a 777LR can fly little over 22 hours non-stop. So I would think beds would be useful there

Singapore Airlines have a few "Suites class" cabins on their A380 planes with actual full-sized beds. It looks like this:

Source: USA Today
A report from one lucky traveler who racked up enough miles to try it:
http://dereklow.co/what-its-like-to-fly-the-23000-singapore-airlines-suites-class/
From the report:

In the Suites, you don’t just lie on a seat that has gone flat.
  Instead, you step aside while the Singapore Airlines flight attendants
  transform your Suite into a bedroom, with a plush mattress on top of a
  full-sized bed. When the adjacent suite is empty, the dividing
  partition can be brought down to create a double bed.

Although it's not mentioned in this report, in most "normal" businesss-class "flat bed" style seats you still must have a seatbelt fastened over the blanket while sleeping (presumably due to safety requirements), so it's not quite the same experience as on a sleeper train, but can come pretty close.

I've often wondered if there's a seat belt system in the suites - beds?

 (image source: Wikipedia)
There were sleeping berths in the upper-class cabin of the Tu-114 aircraft in the 1960es. In 1970es these planes were modified -- the sleeping compartments, as well as other "luxurious" design elements were replaced by standardized seats. The modified version could transport 224 passengers (versus 170 in the original design with sleeping compartments).

Image source (Russian)

Given the noise of the NK-12 turboprops, I wonder how one could really sleep in a Tu-114. But it's interesting to see how a classless society traveled back then.

@PeterKämpf: Probably quite easily - it's quite easy to sleep through loud noises as long as the noise doesn't change suddenly and isn't too high-pitched.

I'm surprised at the answers:
mostly all wrong. Here we go (I used to work doing software internal layouts a airlines)
The answer is:
1) Utility, 2) Safety, 3) Upsell, and 4) Embark/Disembark speed.
Contrary to popular belief, It's not really a concern whatsoever about manipulating internal vehicular space. Airplanes displace a larger amount of internal volume than they require, and the residual space is mostly air, so so long as the bed weighed not more than the chair it replaced it could be done and zero MATERIAL cost to the airline.
But there are other costs: and much bigger concerns
Safety (and by that I mean financial liability in a litigious business space)
Beds aren't done mostly because people underestimate the impact of turbulence. In fact, it's well known, you can double your probability of not dying in a plane by simply wearing the lap belt and staying sitting down.
I.E. turbulence kills as many humans in planes as air plane crashes do: And it's the head hitting the roof that does it. However staff are less lucky in that they get such beds for use on long haul. In fact they are lovely.
While this may seem facile, it's not: in a 3 bunk bed layout the proximity to neighbour beds (above, above and roof) would ultimately cause you to have a  MUCH higher incidence of human/airplane collisions while at rest but under turbulence, which while such impacts would not always mean your head got smashed, there'd be more impacts for both these reasons:  lap belts would be unusable, your head would be nearer obstructions, and a much smaller turbulence jolt would cause collisions.
Similarly landing would be highly problematic and there would be much greater incidents of hospitalisation and death at landing.
Utility
in both senses: an airline can't swap the air frames to different legs as easily, and a passenger can't eat lying down
Upsell
you can't upsell business and first class sleeping pods so easily if economy has them, and airplanes usually lose money in economy and make money in business/first, so they never dis-incentivise upgrading.
Embark/Disembark speed
speed on off MASSIVELY affects profit margins for airlines, every second they are on the floor they LOSE money every second they are in the air they MAKE money. They designed the A380 to be able to on/off at much higher speeds because of this concern. If you have beds it takes ages to get embarked/disembarked.

"I'm surprised at the answers: mostly all wrong." Funny that they make the same points as yours then.

If you can double your probablity of not dying by doing-and-so, that would imply that without doing so-and-so your probability of arriving alive can be at most 50%. I don't think flying is quite that risky, even if you spend the entire trip dancing in the aisle.

Nicely done, @HenningMakholm.  Halving the death rate does not double the survival rate.

Your assesment about turbulence impact depends on the bunks. My guess is that contained, padded bunks would be as safe as seats. But then it would feel like being in a coffin.

the issues just re-iterate that some vendors provide it.. @Transistor what was the OP's question it was "why are there no sleeper planes" and I actually answered it

@HenningMakholm no, it's more correct you halve the probability of dying, I just used a winsome way of saying it.. to encourage people to be aware of something massively under-reported, because it saves lives and (also) I have found such information massively encourages people who fear flying

@Transistor no, they were not at all answers, which is why I came on here to correct them all. In fairness two of the sub points I mention are identified, and given as a whole answer when really they are a part of one point each, and I've made 6 points under 4 categories - for example: repeat demonstrations from history and repeating ad-infinitum that "sleeping pods are available in 1st class", and "they used to years ago", is absolutely not an answer to the question and is merely reference as self evident in my answer

@MrHeelis: Claiming that the probability of not dying is something that can be doubled, and therefore less than 50% to begin with, is something that massively encourages people to fear flying. It seem you have somehow redefined "winsome way" to mean "blatant lie"...

I flew on a sleeper once, about sixty years ago.  I think it was a Douglas DC-6 from Miami to Buenos Aires.  I don't remember much, except that the bunks were a little like the ones on sleeper trains.
When airlines switched from piston power to jets, flying times were cut in half.

As others have stated, there are sleeping berths, but only for those who can afford the premium.
I myself have taken sleeper trains several times; I like them because I can arrive at my destination city in the morning, and still have the whole day to do things.
I can sleep quite well on a plane, in coach, by using a foam collar -- the kind they give to people with neck injuries.  Whether by train, bus, or plane; I can't stand when I have to arrive in the late afternoon or evening, because then the day is shot -- I can't do anything except go to my hotel and get ready to go to bed.  (Unfortunately, where I live, most night flights are banned because of noise restrictions.)

"...there are sleeping berths, but only for those who can afford the premium." Couldn't one make them a bit cheaper, like an economy version of them? Maybe stacking them up a bit.

@Trilarion No, because the cost is directly related to the space they take up (if you want to take as much space as N economy passengers, you'll have to pay the airline roughly what those N passengers would pay in total), and you can't stack them because you need to be able to evacuate the plane quickly. Also, if there's another bunk above you, you'd need some kind of seat belt that would stop either of them hitting their heads on the low ceiling during turbulence. I'm not sure if it's also a requirement that passengers must be sitting for take-off and landing.

@DavidRicherby Your comment seems to answer the question best so far. It's a mix of security concerns and current regulations (which would need to change in order to get low cost sleeper planes). If only it were an answer.

@Trilarion Cooper's answer covers the price aspect; Dave's covers safety.

One more thing: planes go fast enough that you have to take time zones and jet lag into consideration.  Some people stay on the time zone of the city they took off from right until they walk off the plane, and some people change their time zone (and sleep patterns) as soon as possible after takeoff.  (I'm in the latter group; and I almost never suffer from jet lag.)  Sleeping arrangements would have to take both groups into account; some sleeping while others consider it to be daytime.

The incredibly simple answer is that:
You have to be sitting upright in a chair, in a seat belt, for take off and landing.
It's that simple - an "all-bunk" configuration (like a sleeping-bus) is a non-starter.
That's all there is to it.

You have a source for that?

That does not preclude using a bed during the bulk of the flight.

hi @IgorSkochinsky, but obviously then you also need all the seats!  2x the space


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Are there regulations for the minimum amount of toilets per passenger?
Are there any rules or guidelines that define the minimum amount of toilets per number of passengers on an aircraft? I know there are similar rules for cabin crew, emergency doors etc.
It seems to be varying per airline the amount of toilets (similar aircraft type)

This news article says no regulations, at least for the US jurisdiction.  Not sure if that can be considered authoritative.

This is a very interesting question!

(this answer is specific to US laws and regs for domestic flights)
No, there are not. And, in fact, it is perfectly legal to fly with ALL of the toilets broken and unusable. No restrictions on flight time, either. The airline is required to notify all passengers that the flight has no working toilets. (I'm not sure if any compensation is required for passengers electing to not board the flight).
The Department of Transportation does provide the following in their Aviation Consumer Rights rules:

(in the section discussing tarmac delays): While the aircraft remains on the tarmac lavatories must remain operable and medical attention must be available if needed.

Although it's obviously not possible to make the lavatories available during a tarmac delay if the lavatory is broken, there are no rules prohibiting the flight from departing if the lavatory is broken.

This is a horrible answer! (From the passenger's point of view...)

Agree... several "horror" stories in various media from over the years.  I think one of the more recent ones was about a year or so ago on an American Eagle flight. The plane was at an outlaying field with no maintenance, destination ORD. The plane had to go to Chicago to fix the lav no matter what, so they had two choices: bump everyone to different flights and fly the plane empty on a maintenance ferry... or just bring everyone along, and they could "tough it out". If I was a pax with bladder problems, I think I'd ask to be rebooked... otherwise, I would just tough it out.

Hand out empty bottles?

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When does a pilot and when does a co pilot start/land?
I am wondering if there are certain rules about when a pilot and when a co pilot starts or land a plane. As far as I understand a co pilot's job is to support the pilot. Do they talk to each other during the flight and decide that spontaneously or is the decision already done long time before a flight and how?

I long for the day when the term "co-pilot" is forgotten. Pretty much every airliner needs at least two pilots to fly it, and they both support each other. Yes there is always one with greater authority, but there is no such thing as a half-pilot (cruise-relief pilots perhaps the exception...).

Before the flight starts, one of the two pilots is always the "PF" (Pilot Flying) whose job is to fly the aircraft, and the second pilot is "PA" (Pilot Assisting) whose job is to deal with the communications, aircraft systems and perform tasks as requested by the PF to assist them in flying the aircraft.
It is usually the captain that does the preflight briefing in the cockpit, announces any anomalies for the aircraft (for example, the APU might be unavailable due to maintenance, etc.) and all this is communicated to the rest of the flight crew.
Then, it is decided who will fly this leg of the journey, and that pilot assumes the control, and the other starts communicating with the tower/ground/dispatch and adjusting the various systems, etc.
The ultimate responsibility rests with the captain and if there is any abnormal situation (such as a flight systems malfunction) or other condition, the captain can always assume the duties of "PF".
The exact manners on how this is done differs, but for the purposes of the flight log it is always annunciated. So the PF might say "you have control" and the PA might say "I have control" to indicate that the flying roles have switched.
Crew management is a complicated topic and is a complete discipline and many airlines spend a great amount of time training and teaching crew management to their pilots.

Nice answer, but are there any regulations on how to decide who is PF and who is PA before the flight? Do they both discuss it and decide it depending on their moods or are there any regulations for that decision how it is made?

The only regulation I know is that the captain is the one ultimately responsible for the flight, no matter who is flying. For the purposes of incident reports, it is noted the PF (Pilot Flying) vs. PA (Pilot Assisting). As far as I know, there are no regulations on who gets to fly which leg, and is decided between the pilots before the leg starts.

In many parts of the world, "Pilot Assisting" is known as "Pilot Monitoring". I agree that there are no regulations for this but it should be covered in the operator's manuals.

Also PNF, pilot non-flying.

You've asked a many-faceted question, the answers to which depend a little on FAA regulations in the U.S. but mostly on the policies and culture of individual airlines. Also, it's the captain's airplane, which means he/she may have, should we say, his/her own way of doing things. How much that might vary from the airline's "standard" can vary greatly, especially when you compare what would be typical in, say, the U.S. versus other countries, and especially third world countries. You could write a small book on this topic. A few items I can think of offhand follow.
All four of the airlines I flew for (two commuters and two 747 carriers) required the captain to do the engine starts. These days there is FADEC, so it's an automated procedure. Pre-FADEC, somebody had to move the lever that introduced fuel to an engine and, in the case of a hot-start, had to cut off the fuel and handle the heat properly. Failure to do so meant you might trash a multi-million dollar engine.
At all four of my airlines, the usual procedure was for the captain to fly the first leg and then alternate with the f.o. after that. At the two 747 carriers, however, new captains were required to do all the landings for their first 100 hours.
The second commuter I flew for had a rule that when the nose-wheel steering of the aircraft (SA-227 Metroliner) was inoperative, the captain had to taxi the aircraft.
The second 747 carrier I worked for had a rule requiring the captain to do all the taxiing. I ignored that rule as I felt it was unnecessary and ill-advised.
There were rules that required the captain to do approaches when the weather was below certain minimums.
The standard way of doing things was always well covered in initial and recurrent ground schools, simulator training, and CRM (Cockpit Resource Management) classes and sim exercises. IOE (Initial Operating Experience) for new cockpit crew as well as later periodic line checks by check airmen provided continuing standardization.
During a flight, the pilots continually talk to each other as required, and on long flights typically a fair amount of visiting, although below 10,000 feet only essential conversation is the rule. There is an old joke that goes something like, "When pilots are in the cockpit, all they talk about is women. When they're with women, all they talk about is flying." Obviously it's a sexist joke and is, I hope, disappearing with increasing numbers of women in the cockpits. It was never really true anyway.
Concerning verbal communication, both 747 carriers, as a part of Cockpit Resource Management had a procedure for handling subtle incapacitation of a pilot. If at any time you did not get a verbal response from your fellow pilot when a response would normally be expected, you were to turn to him and say distinctly, "Are you okay?" If they didn't answer, you were to take control of the aircraft.

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How do elevator servo and anti-servo (geared) tabs differ?
(Community work) Image shows tab deflection direction in relation to an upward deflected elevator.
How do elevator servo and anti-servo (geared) tabs differ in handling? How to decide on which tab to use?

I'm not sure the image helps...

BD-5 and Piper's used anti servo tabs, to add resistance to the controls . KC-135 uses servo tabs on the controls to allow manual reversion if the hydraulic boosting systems fail.

There is some confusion on the different types of tabs that can be found on aircraft: servo tabs, geared tabs, trim tabs.
The servo tab is an aerodynamic lever, it is connected directly to the pilot flying controls. When they move the controls, they deflect the servo tab only, and feel aeroforces acting upon the servo tab only. When the servo tab deflects, it creates a force moment on the control surface ( elevator, aileron, rudder) which then deflects the control surface until aerodynamic moments are in equilibrium. If there is no airspeed, deflecting the servo tab has no effect on the control surface.
The geared tab changes the flight control forces to either increase them (usually in small aircraft) or reduce them (an arrangement used in the pre-hydraulic past of airliners). The control surface is directly connected to the stick/pedals - deflecting them causes the control surfaces to move. In order to alter control forces, a geared tab moves relative to the control surface:

For increasing stick forces, in the same direction as the control surface. Wiki and others mention anti-servo tabs, a less confusing name would be positively geared tabs.

For decreasing stick forces, in opposite direction of the control surface. Whether there is airspeed or not, the geared tab always deflects by a mechanical linkage when the control surface is deflected.

The trim tab has a constant angle relative to the control surface. The angle can be changed by extending/retracting a mechanical link, via a trim wheel or an electric motor with a screw jack.

Usually (and on the image in question), anti-servo tab is a force amplifier. It moves in the same direction as the surface and increases the force. It is used when the controls would otherwise feel to light for precise control.

And how does it move in the same direction as the comtrol surface? By a geared mechanism?

Anti-servo == geared, so, yes. (servo and anti-servo work very differently)

Point being, if we strictly follow the nomenclature, anti-servo tab would be a misnomer necause the tab does not have a motion amplification servo function..The fixed gearing, whether it be a force reduction or increase, would make it a member of the Geared Tab family.. But perhaps I'n nitpicking, or not aware of a past marketing campaign.

Agree, it is a misnomer. But my point is that geared, while it can be both reducer or amplifier, is more often amplifier than reducer.

OK I'll include that in the answer.

Servo tabs assist the pilot (like trim). Anti-servo act against the pilot.
The all flying stabilator on a Piper Cherokee, as I recall, uses anti-servo. Since part of the stabilator is ahead of the hinge point, the anti-servo tab on the back aids in both control feel (making it not too light) and in return to center characteristics.

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text:
Why stall on 2D faster than 3D?

why cl on 2D is better than 3D. and why cl 2D stall faster than 3D?
what happens when CP continues to move forward on the wing. and what happens when CP continues to move forward on the elevator.

Related: https://aviation.stackexchange.com/questions/14508/what-is-the-method-to-calculate-a-finite-wings-lift-from-its-sectional-airfoil

Ade, please be aware that asking multiple questions in the same posts is generally frowned upon. In this case they are quite close to each other, so an answer should be able to cover all your questions, but please try to avoid repeating it.

The 3D-wing allows for air to flow over the wingtip into the low pressure zone over the wing, thus reducing the overall pressure differential and reducing overall lift.
This explains the stall at higher AoA because the additional airflow over the wing surface "energises" the air. Flow seperation happens when the kinetic energy is equal to the pressure differential that the airstream flows into, so if you can increase the kinetic energy, you can decrease the tendency of the airstream to separate.

Moving my answer to a comment: It may be due to initial assumptions -- I would think that a 2D model assume infinite length of the airfoil, whereas a 3D model would necessarily have a finite length.

You could phrase the question differently: why does a wing with low aspect ratio need a higher Angle of Attack to provide the same lift, and why is maximum lift lower? Because the pressure can escape over the wing tip. The larger the wing tip, the larger the effect.
Yes a low AR wing can reach a higher AoA than a high AR wing, but only because it produces less pressure differential, therefore less lift.

Stall happens because the flow cannot follow the airfoil. If you have a 3d wing,  the pressure difference between the pressure side (below the wing) and the suction side (above the wing) can be reduced due to wing tip vortices —> less lift —> smaller $c_L$. They are generated because of the pressure difference. This will reduce the adverse pressure gradient above the airfoil and hence reduce flow separation. These vortices additionally inject energy into the boundary layer (pushing the air toward the airfoil) such that the flow can better follow the air foil despite the adverse pressure gradient. Hence, stall is later for 3d wings.


text:
What is hinge moment?
What is hinge moment?
Why in the process of calculating it we must calculate the coefficient of hinge in 2D?
Why the distribution of airfoil thickness at 90%, 95%, and 99% of the line should be considered?
Why is the line used for his (cf= line form hinge line to trailing edge) (cb = line from hinge line to leading edge) using a perpendicular line with Λ_(1/4) wings?

The hinge moment is the moment acting about the hinge line of a control surface. Simply put, it is the force that must be overcome to move a particular control surface. At any given dynamic pressure and airspeed, the hinge moment will vary with angle of attack, the amount of control surface deflection, and trim tab deflection. Not an easy concept and not one which is generally taught to pilots, however becomes critical for engineers who design control systems for aircraft.


text:
What is the origin of the waypoint CLAWW and PAHTI(New England region)?
I'm the reading the book "Sayfaring".
There are two waypoints I don't get the origins in the sentences.
1) CLAWW
"Boston has lifted a particularly intricate constellation of itself
into the ether above New England. There is PLGRM, for the
region’s history; CHWDH, LBSTA and CLAWW for its food"
2) PAHTI
"Even the region’s speech –WIKID, followed by PAHTI – seems to be mapped

Aha. Someone finds some interest in Bosron-talk.

@SMSvonderTann I'm from the home of the pilgrim fathers so the lingo is familiar ;)  I'm also a "foodie" so New England sea food is no stranger to me.

Related: A Pilot Explains Waypoints

Somewhere in the basement of the FAA charting office is one person, a bag of Scrabble letter tiles, a 5-tile template, and a bottle of cheap booze - we're talking plastic bottle vodka. ". . . . And that's how waypoints are named!"

Read it as "wicked party" and Boston is famous for sea food, including crab claws.  Chowder, lobster and claws.

Yup, that is correct.

A reference to the Boston Tea Party, perhaps?

@RalphJ Bahstn's fahst wicked pahti!

@ymb1 Nope, that waypoint is in the LGA/JFK area.

@ymb1 Yup, have heard that before.


text:
What is the origin of the waypoint WORUM (neayby Houston)?
I'm reading the book "Skyfaring".
There is a sentence "TQELA, WORUM, CRVZA (beer), CARNE (meat),
QUESO (cheese) for the city’s cross-border
culinary traditions"
What is the origin of WORUM?
Is it related to some food?

Mezcal


text:
Is this the first single-engine helicopter clean-sheet design since 1976?
An upstart in the helicopter business, Marenco Swisshelicopter, claim their SKYe SH09 is:

“the first single-engine helicopter designed with
  a clean sheet of paper” since 1976.

If you compare this market with the
  automotive market, it’s like we’re competing with cars from
  1976 whose only upgrades have been airbags and a GPS
  scrolling map. The market has not seen real innovation in
  years.

What 1976-design are they referencing and how accurate is their claim?

Most modern helicopters use two engines for added safety. This reduces the field of competing designs. Also, a good engineer will always leave proven details unchanged and focus on improving flawed designs. So it is hard to prove that a new design from an established helicopter company will truly be a clean-sheet design.
The possible new designs from 1976 could be:

Aerospatiale AS-350 Écureuil: First flight 1974, introduced 1975. Note that the AS-355 is a two-turbine variant of the single-turbine AS-350.
Robinson R-22: First flight 1975, introduced 1979. It has a single reciprocating engine and was indeed a clean-sheet design by Frank Robinson who started the company in 1973. He had worked previously at Bell Helicopter and Hughes Helicopters.

It may be that some ultralight helicopters like the Mosquito are also "clean sheet" designs as well, but they don't make that claim on their site.

@RonBeyer: Excellent remark! I did not think of them first, but their category was only defined in the Eighties, so all of them are younger than the R-22 and must be clean-sheet designs, at least in their first iteration. Probably Swisshelicopter made the same mistake.

thanks for your answer! could you elaborate a bit on the accuracy of the claim? you say good engineers (incl. those at existing companies) "leave proven details unchanged and focus on improving flawed designs". But Marenco's claim is exactly in improving the design, not the details. Specifically: "carbon fibre cockpit, glass doors, removable seating, rear clamshell doors and a large load capacity", has this really not been done before in this market segment? (I guess they're betting on one engine being save enough when well maintained and far cheaper...?)

plus some additional features touted: bearing-free rotor system, shrouded tail rotor and material choices like composite cell and glass cockpit...

@mb21: I don't know whether a carbon fiber cockpit is an improvement - in a crash it will splinter and cause bad cuts where metal would only bend and absorb the energy. And other helicopters had transparent doors before. The load capacity comes with the size of the helicopter - no surprise here, too. Yes, by starting from scratch you avoid the trap of "good enough", but I do not see how the SH09 is more than another iteration of a proven concept. The claim of "first clean-sheet design since 1976" is surprising and good marketing, but need not signal a better product.

One might even argue that clean sheet design would make for an inferior product. Mature designs have spent some number of years working out the kinks. A new design is an unknown.


text:
Curvature of Earth - Airplane
One of my co-workers is a FLAT Earth believer. I have tried all kinds of logic and facts to disprove his belief.  He is not the sharpest knife in the drawer so trying to explain Gravity, atmosphere moving with Earth, etc is difficult.  I have read the threads trying to explain if pilots make adjustments for curvature. Answers/explanations are all over the place...
What I need is a very uncomplicated explanation as to how a plane tracks along with the curvature of the Earth WITHOUT pilot making adjustments.

Could you try and prove it to him in a different way? For example, if you have the sea close to you with bigger ships visible, you can quite literally see the bigger ships "sink" into the horizon due to the curvature of the earth.

Imagine walking around a very large cylinder. Put your hand on the cylinder wall and walk. The larger the cylinder, the less obvious the curvature is. Make it big enough, you might not even notice at all, but keep on walking and you'll come back around. The "adjustment" is "automatic".

You might have better luck with the answers over here: What is the simplest way to prove the Earth is round?

If the Earth is flat, then there is an edge. Ask him to produce pictures of that edge, or explain why no such pictures exist.

Related

@Pondlife I would almost consider that a duplicate, but a flat-Earther would reject the premise of the 8-inch-per-mile drop because they reject the premise that the surface of the Earth is, in fact, the curved surface of a spheroid.

In an age of satellite imagery, deep space probes, and detailed mapping of other planets, how can anybody still believe the Earth is flat? Unfortunately I meet stupid people like this quite often, and usually the best thing is to let them continue on believing because no amount of arguing or scientific evidence is going to change somebodies (poorly held) beliefs, especially if they aren't inclined to accept evidence to the contrary. Just move on with your life and avoid the topic with that person if you can't avoid the person altogether.

From experience with conspiracy theorists there is no way to prove the earth is round. No amount of science, math, or logic will change what a person wants to believe.

A battle of wits with an unarmed person is an exercise in futility.

This is an unanswerable question.  While the Earth being round is certainly an easily stated fact, it would be a matter of opinion of how best to address your co-worker (if they are even to be addressed at all.  Frankly I assume any explanation we might offer would fall on deaf ears.)  Voting to close.

Have you tried turning his brain off and on again?

Give up.  I have come across these people before.  They make moon-landing deniers look smart.  Never argue with an idiot. They will drag you down to their level then beat you with experience.  Nothing you say, do, experiment with or draw, will change this persons mind.  Even if you could somehow put them into orbit so they can see with their own eyes, they would twitter on about fisheye distortion in the windows, mind altering drugs pumped into the air etc.  They will invent a new explanation for why anything you say is wrong.  Voting to close.

Why do you try to prove the accepted state-of-the-art of science? Your colleague sees the necessity for an diverging view, have him prove it to you.

Nothing you say can convince this person that the Earth is round.  You need to show him.
Find a hill that is a few hundred feet high.  One of you stands at the top, the other at the bottom and observe the sunset.  You will, of course, be accompanied by a trusted flat-earth friend of his to validate your observations.
Each person will note the time that the sun disappears below the horizon.  Your times will be different.  You can even use math to calculate the expected time delta if you really want to drive your point home.  The higher the mountain, the greater the time delta.  Also, if you're at the top, you can flash him with a mirror to prove that you can still view the sun.  Be careful though...this might blow his mind.
This is a direct observation of the curvature of the Earth.  A rational person will accept this as proof of a curved surface.  An irrational bozo will continue to offer absurd theories.  Please let us know how your friend responds.

"the sun disappears below the horizon", it just proves the Sun orbits around the Earth.

If you can predict the time delta based on a calculation predicated on the known curvature of the earth, a person can't conclude anything other than that the earth is indeed round.  If a person wants to start questioning the particulars like our distance from the sun or speed of rotation then all bets are off.  At some point you have to just let stupid people be stupid.


text:
What happens when the surface ends at the laminar zone of the boundary layer?
When a body travels through any fluid, due to viscosity of the fluid a boundary layer is formed around the surface of the body which separates the velocity of the fluid inside the boundary layer(near the surface of object) to velocity of the fluid.The boundary layer consists of three zones laminar, transient and turbulent zones respectively.
Is it compulsory for all the three zones to exist in a boundary layer? If we consider a small smooth surface, is it possible that the surface ends at the laminar zone of the boundary layer and there is no turbulent zone in boundary layer over the surface? And if it is possible will there be a low pressure zone at the end of the surface or something?

Likely related: On The Critical Reynolds Number For Transition From
Laminar To Turbulent Flow (here).

Then you get a fully laminar boundary layer without transition. This can happen at very low Reynolds numbers, especially if no steep positive pressure gradients are encountered.
A steep pressure rise can lead to separation, and if the boundary layer does not change to a turbulent one, this separation can be final, with no re-attachment of the boundary layer. Then the attached flow ends before the body ends, but still the boundary layer is fully laminar.
It is not compulsory for transition to happen. If the flow is stable (either due to a negative, stabilising pressure gradient or due to very low Reynolds numbers), the boundary layer will stay laminar for its full length.


text:
How does headwind influence the results of a pitot tube and therefore the airspeed indicator?
What I know so far
I recently read about pitot tubes and their use in aircraft. For the basics I consulted Wikipedia, and also went through the definitions for airspeed, groundspeed, and the various other airspeed definitions (TAS, IAS, EAS, CAS). Furthermore I made myself familiar with aircraft speed indicators.
At first everything seemed logical, I thought I understood the working principle. But then a few days ago I came across the question how wind (headwind, for that matter) is accounted for on the airspeed indicator.
Question
Assume an aircraft that is standing still on the ground, experiencing a 60 kt headwind. Will the airspeed indicator show anything that is related to that headwind? Why/why not?

@mins Thank you for the video! I actually could have come across it myself.

You can imagine your hand is the speed sensor (like when you put your hand thru a car window: You feel the wind, regardless of whether it's the car moving or the wind. If you drive into the wind the speeds add, if you drive in the direction the wind if blowing to, the speed subtract. If you are at the same speed than the wind and in the same direction, then your hand feel no wind, even if actually the car is moving. An airspeed sensor (pitot probe) works exactly on this principle.

The pitot-static system (and the airspeed indicator) doesn't care about the speed of the aircraft with respect to the ground. It is concerned only with the speed of air with respect to the aircraft (that is why it is called airspeed and not groundspeed indicator).
So, if your aircraft is on ground and experiences a headwind of 60 kt, the airspeed indicator will show an airspeed of 60 kt, in an ideal case.
This is important because the wing generates lift depending on the airspeed, not the ground speed (forgetting about stuff like ground effect, etc.). This means that if an aircraft is parked on the ground and there is a headwind of sufficient velocity, it will try to lift the aircraft up.

So if the aircraft is accelerating into this headwind (for take-off purposes) the airspeed indicator (IAS) will start at 60 kt, go down until the aircraft exceeds 60 kt and then go up again?

@pat3d3r Not quite. If the aircraft is sitting stationary on ground in a 60 knot headwind, the airspeed indicator (ASI) will start at 60 knots (there are 60 knots of air moving over the aircraft with a groundspeed of 0 knots). As the aircraft is accelerated to 20 knots of ground speed, the ASI will show 80 knots (as there are 80 knots of air moving over the aircraft). If the aircraft accelerates to a ground speed of 100 knots, the ASI will show 160 knots (as there are 160 knots of air moving over the aircraft).

@JonathanWalters Ok, that makes sense, especially in respect to the differentiation of airspeed and groundspeed. Thank you!

@pat3d3r What you described in your first comment is sortof what would happen if you had a 60 kt tailwind though.  Because of the design of the pitot tube (pointing forward), it would actually start at 0, remain at 0 until reaching a ground speed of 60kt, and then accelerate as the aircraft continued to accelerate.  Note that in many cases due to the designed of the aircraft and the length of the available runway, it may not be able to even takeoff with such a strong tailwind.

@Lnafziger I still have trouble understanding the physics behind it. Taking the tailwind situation: During acceleration of the aircraft the air mass of the tailwind is keeping the incoming air (due to acceleration) out of the pitot tube until incoming air speed exceeds the tailwind?

@pat3d3r Correct, IF it were a bi-directional pitot tube, it would show as -60 kts, which would increase towards 0 as the airplane started moving forward.  Since the pitot tube is not though, it will indicate 0 until the aircraft is moving forward relative to the air. There is no forward movement relative to the surrounding air as long as you are moving forward at less than the speed of the air though.

@Lnafziger Got it, thanks!


text:
Are there additional structural measures in airliners with asymemtrical seating arrangements?
I was recently flying onboard an A220 and was surprised by the asymmetrical five abreast seating arrangement.
Are there any structural measures (e.g. counter weights, ...) to balance out the aircraft specifically because of the asymmetrical seating configuration?

There are lateral center of gravity limits, mostly to deal with fuel imbalance and to deal with controllability and trim limits in a worst-case flight configuration,like an engine failure right after rotation.
A cabin load offset of a foot or so from center line, because the aisle was offset, has no significant structural impact and will have a trim impact (roll tendency) that is negligible, compared to other effects like fuel imbalance. In fact you can have certain amount of variability in roll trim from airplane to airplane just from variations in symmetry of the wing structure (twist). Everything has tolerances.

Ok, thanks for the explanation.

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text:
How to prepare for a PPL license (before officially starting the course)?
I am aiming to get my PPL(A) licencse next year, the official start will be around spring, when my savings plan is due.
I have lately been able to free up my schedule a little for the current year, and I am thinking about using this spare time to prepare for the PPL course.
To not make the question too broad I've compiled three core questions:

Does it make sense to start practizing with a flight simulator?
The theoretical part of the license can also be taken as an online course which I can afford financially already.  Should I do this now, or attend regular classroom training with a FI next year?
How meaningful are trial lessons?

For completeness, I am in Europe.
Thank you for your advice in advance.

Your first question should be covered here: Can Microsoft Flight Simulator help me learn to fly (or make me a better pilot)?

@Bianfable: Thanks, I already went through that post, but felt like including it here for sake of completeness.

If you haven’t taken at least one intro flight I recommend it.

Don’t do anything in a sim that you haven’t already done in a real plane with an instructor. Unlearning bad habits can waste a lot of money.

Much of this depends on how quickly you plan to get your PPL. If you are going to try and get through it in a few weeks then it makes sense to get all your ground work done ahead of time, including taking the exams. Most people self-study the material, which really isn't that hard to learn. A good deal of material you read won't make sense until you are actually flying, which is not a problem as it will later. If you are going to do your PPL over a longer period of time then there's no point in cramming it all before you start and you can take it at your own pace.
When I started my PPL I had self-studied a great deal about the mechanics of flight and understood the basic controls, which I found really helped me get started. My many, many hours on flight simulators was both a help and a hindrance as I had to un-learn some bad habits. If you do flight simulator by all means enjoy it, unless it's instructor-led you won't get that much out of it.
One thing that comes in useful is learning the in-memory checklists (for instance engine failure, fire, etc) and the relevant speeds for the airplanes you will be learning on.
At the end though my advice would be not to overthink it, many people start their PPL with no preparation at all and do just fine.

@pat3d3r worth noting: checklists can be operator dependent and "fluid". If you know what plane(s) you will be flying and have access to POH, learn the memory items as suggested, but leave the checklists untill you know how the flight school manages them. During my PPL there were several updates to checlists.

Agree with this. The training covers it well, you don't need a lot of prep. But, personal opinion, two areas that just 'take time' to master are weather and radio comm. Understanding weather patterns takes time. Study up on aviation weather and practice reading forecasts and seeing what it really means. Also listen to an aviation radio or LiveATC to get used to the phraseology and following the conversations.

For completeness: Read some material about radio communication. +1

Watch some YouTube videos from reputable flight instructors

@GdD: Thanks for the insight! This perspective really helps.

@Jpe61: I have a rough idea of the planes from correspondence with the flight school, so I will try to get my hands on the relevant POH.

@Gerry: The advice about radio communcation and LiveATC makes sense, though I did not think of it. Also, weather is nothing I am overly familiar with, so certainly good points to start. Thanks!

@PeterKämpf: With your advice I just discovered some EASA documents about radio communcation and phraseology. I'll add it to my preparation list, thanks!

@pat3d3r - I’m probably not supposed to give actual links to specific resources but there’s a YouTube channel named “FlightInsight” that has some pretty good content.

I'm unfamiliar with EASA resources, but the FAA has a very good document on aviation weather. As far as I know, weather follows the same laws on both sides of the Atlantic ;-)

@Gerry: Since you mentioned LiveATC I have one quick follow-up question: I have listened to it mostly with standard headphones, and have trouble understanding things acoustically. I suppose it gets easier when I know what exactly to listen for, but generally, is the sound quality better or worse when actually flying (with an aviation headset)?

Yes it gets easier as you become familiar with normal communications. The audio quality is about the same. It's a factor of the AM radios and allocated bandwidth. The only difference in the plane is noise. A good active noise reduction (ANR) headset helps tremendously. Passive headsets attenuate the noise but there's still a lot of lower frequency noise that gets through. It's definitely better than when I started flying. Headsets were ridiculously expensive (about $1500-$2000 in today's money). We had foam earplugs and listened through a little speaker and had to use a hand mic.

@Gerry: OK thanks, good to know.

From my flight instructor:

most pupils they get who claim to have time in MSFS have ingrained very bad habits that are dangerous and really slow them down in learning to fly properly
It CAN help with cockpit familiarisation, but you tend to rely on instruments way too much, rather than on piloting and your surroundings (simply because of the limits of the computer simulation, I noticed that myself, forcing yourself to look out rather than down can be hard in the beginning)
It certainly helps understanding how the control surfaces affect the aircraft, but as there is way different control feedback on the computer this can also be a hindrance.

Overall, he prefers pupils with either no simulator experience or very extensive simulator experience using high quality models and simulators (not the gamified stuff that's default in MSFS) and using real life manuals and procedures in the simulator rather than just hopping in and going.
ATC procedures in EASA airspace at times being quite different from the US centric ones in MSFS (especially for VFR) doesn't help either.

Thanks, this is very helpful!


text:
Forces acting on ram air parachute (for pulling ships)
I recently stumpled across this question about the ram-air parachutes for use in pulling ships.
In this answer it is stated that the parachute needs to travel perpendicularly to the ship's motion in order to work against the hull drag in the ocean.
This is something I do not quite understand, even after watching videos that confirm the chute actually going sideways.
I have consulted the usual lift-drag diagrams, but have not been able to apply them to this case her. Can someone briefly explain the forces at work with their respective vectors, preferably with a diagram?

This belongs on a sailing forum.

@JohnK: The initial question seemed to fit here, so I thought this one will too, since they are directly related.

@quietflyer: OK thanks. I am still having a hard time figuring it out. Edit: Thanks for the links, didn't see them at first.

Reposting to revise-- previous comments referred to these links --https://aviation.stackexchange.com/questions/99796/why-a-kite-flying-at-1000-feet-in-figure-of-eight-loops-serves-to-multiply-th#comment278440_99796  -- key point is that you want the kite to pull using Lift rather than Drag, and you want the kite to be moving at a high airspeed, not stationary relative to the boat-- it's complex and the statement you quoted in the other answer is not really accurate. The lift vector can exert some pulling force even if kite is stationary relative to the boat and directly "ahead" of it--

(ctd) especially if the kite is well above the boat.  But that's not the best way to use the kite to pull the boat.  This may help -- https://aviation.stackexchange.com/questions/99796/why-a-kite-flying-at-1000-feet-in-figure-of-eight-loops-serves-to-multiply-th#comment278588_99797

As what amounts to a sail, tethered to an object to pull it through water by generating lift at extremely low Reynolds Numbers, a fancy more efficient spinnaker on a reach in effect, I think the expertise on a sail boat design channel might be better suited.

Two perpendiculars make 180 degrees, force opposite the ships drag.
It's the same with iceboats.  Instead of using wind as propulsion, wind is used to move the sail.  The lift from the sail (more efficiently) creates propulsion.
The sail is essentially a wing.  Sailplanes use gravity as propulsion to  move the wing, and the perpendicular wing lift more efficiently resists gravity in the vertical direction.  This is why a sailplane has a lower rate of descent than a parachute.
Making the kite move perpendicular to the direction of travel enables the more efficient airfoil to lift opposite the ships drag.


text:
What's the difference between feathering, and flapping in a helicopter?
Aren't both methods used to increase angle-of-attack (AoA)? Blade flapping will change the blades level, while feathering will change the pitch, but if both increase AoA why not just use one method?

Flapping and feathering are both rotations about a hinge, with each movement having its own axis of rotation, as shown below in a figure from Raymond Prouty, Helicopter Performance, Stability, and Control. It is a top view of a 2-bladed rotor with hinge offset.

The feathering axis allows the blade to be rotated lengthwise. The pilot initiates this movement, via the cyclic and collective control stick, and the Swash Plate transfers this input so that the blades rotate about the Feathering Axis.
The Flapping Hinge allows the blade to rotate up/down. They could point straight up - in normal operation the rotation of the blades produces centrifugal forces that are higher than the lift forces, and the blades point more or less horizontal. The Flapping Hinges are there for counteracting lift dissymetry.
Flapping was discovered as a cure for rolling over when airspeed increased: a blade moving forward has more lift than a blade moving aft. The flapping hinge allows the forward moving blade to move up, effectively reducing the Angle of Attack. Likewise, the aft moving blade descends, increasing the AoA. The effect was discovered by Juan de la Cierva when he constructed his autogyros in the early 20s.

Flapping, the vertical up/down movement of the blades, is not directly controlled.  What a pilot controls is the blade feathering or pitch angle.  Increasing feathering / pitch generally increases the aerodynamic forces on the blades, which changes the flapping.  Unless the rotor and blade are infinitely rigid, which would cause other problems, flapping will be a (often useful) side effect of feathering.
All else equal, higher feathering / pitch at a certain azimuth leads to higher flapping 90 degrees later in the azimuth.  This link explains the 90deg offset in technical details:
Helicopter Flap Dynamics


text:
How does wind speed affect helicopter rotor speed?

So on the left it shows wind flowing with the direction of the rotor, yet it represents that it would reduce the rotor speed. I'm wondering how it does this, wouldn't the wind minimally help increase rotor speed by pushing it? Even if the effect was minimal to the point that it was neutral, why would it slow the rotor down?
If anyone could explain that would be great! Thanks.

Equal and opposite on the other side it would be pushing against the blade and cancel out the effect.

@Ron Beyer, the relation between drag and speed is not linear so it does not simply cancel out.

Are you perhaps misreading this?  The 90 and 110 refer to the speed of the relative wind (the airflow)  not the tutor speed)

Assume the rotor is moving with a constant speed in relation to the body of the helicopter. If the rotor has a headwind (the left side), it will move at a slower speed through the air. It's sort of like understanding the difference between airspeed and groundspeed.

As you suspect, the angular speed (speed of the rotor around the rotor axis) doesn't change. What you miss is the graphic is not about angular speed, but  about linear velocity of a given point of a blade relative to the airflow.


text:
How would an airfoil react if it was flown backwards?

Out of curiosity what would happen?
Would pressure on both top and bottom flip? or stay the same or act as a normal wing with less lift?
I'd assume it would still take longer to travel over the top than the bottom. Then conservation of energy takes effect and produces lift due to pressure, just wondering what negative effects happen?

Sounds like you want to subscribe to the "equal transit theory" of lift, which has been disproven.

Related : Is there an aerofoil that gives reasonably good lift for both air flow directions: forward and backward?

Wow, your picture shows the airfoil at at an extreme negative (backwards) angle of attack.  Obviously it would "dive for the dirt" and crash violently into the ground.  End of story, enough said.

What would happen? Flow separation on the suction side, but it would still produce lift like a regular airfoil. The L/D ratio would be lousy, however.
Only at a small angle of attack range will the wing show attached flow on both sides: When the stagnation point is right at the tip of the trailing edge. This behaviour is similar to that of a flat plate and produces a rather limited range of useable lift coefficients and substantially more drag than when used properly. But still you get more suction on one and more pressure on the other side. The blunt rear edge will cause flow separation at all angles of attack and substantially increase pressure (or form) drag.
An airfoil with a blunt trailing edge has an advantage over a flat plate because it will perform acceptably over a slightly larger angle of attack range, but still this will be no comparison to the behaviour with the blunt side facing forward. Indeed, the front of an airfoil needs to be blunt to allow its use over a larger angle of attack range, while its rear end needs to be pointed to reduce the area over which the flow separates.
Now I feel I should drop a line or two about the cause of lift. Essentially, a wing creates lift by accelerating the air that flows around it downwards. The inclination of the airfoil will already be enough to cause this acceleration, regardless which side faces forward. The plot below shows how several airfoils perform over the first 180° angle of attack.

Lift coefficient over the first 180° angle of attack (picture source)

Misunderstanding of cause and effect. The acceleration of the air is not the cause of the lift. How can it be? the air is accelerated after it hits the airframe. The acceleration is simply a consequence, (that means an effect, not a cause), of the Principle of Conservation of Momentum. This principle is of course very, very important, and all aviators need to understand it, but it is not the cause of lift. Lift is caused, by the result of the impact of the atmosphere molecules on the surface of the airframe.

@CharlesBretana "impact of the atmosphere molecules on the surface of the airframe"? Do you really mean Newton's impact theory? Maybe read this instead

No I do not mean Newtons Impact Theory. Your answer to that other question is excellent. It is in more detail, exactly what I mean. Perhaps you misunderstand what I am saying above. when I say impact of the atmosphere molecules on the surface of the airframe I am talking about the same thing you are talking about when you say The molecules will bounce against the wing skin more at the lower side than at the upper side, and the difference is lift. The difference you refer to is the difference between the forces exerted by all the molecular collisions on the  bottom and the ones on the top.

Actually, as I would state it, Lift is just the normal (normal to the airspeed vector) component of the vectorial sum of all the forces exerted by ALL the molecular collisions of air molecules hitting the airframe, just as Drag is the Parallel component of that same vector sum.

@CharlesBretana Then we are on the same page. To use Newton again, force is mass times acceleration. The air gets accelerated at the same time it is pushing against the wing. No need to confuse cause and effect: It is all happening at the same time.

Yes, we are on the same page, almost... But I believe basic understanding is dealt a severe blow when we confuse cause and effect. They do indeed occur close to the same time, well, very close to the same time, but F=ma has two variables. It would be absurd to say that the Acceleration causes the Force.

@ymb1, The only process that attempts to disparage the notion of cause and effect is the "spooky" action at a distance, in Quantum Mechanics, that purports to explain Quantum Entanglement.  Are you saying that F=Ma is an example of Quantum Entanglement? It may not be necessary to regard the equation of motion as a cause-effect relationship, but that doesn't mean it is not a cause & effect. It is still cause and effect, regardless of whether you regard it that way or not

@ymb1,  And they are not simultaneous! Heck, the entire notion of simultaneity, by Einsteins general Relativity, is proven to be a perceptual fiction. Newtonian Mechanics is just wrong. Any two events in Space-Time, can be defined as either A Before B, A after B, or are not even in each other's time cone (they cannot be aware of one another) see https://en.wikipedia.org/wiki/Relativity_of_simultaneity

@ymb1, In your tanker example, before the tanker releases the water. The Force is the Lift on the wings. The mass is the mass of the tanker and water. The resultant acceleration is 32 ft/sec2 (if in Level flight). After the release, the force is the same (until the pilot eases off on the back stick to lower the AOA, lift does not change), the mass is the mass of the tanker without the water, and the acceleration is greater than 32 ft/sec2 by some amount.

@ymb1, Also, in GR, an accelerating object will ALWAYS feel the force, at least if you measure the acceleration properly, in a non-accelerated (free-fall) frame of reference.

If you take the pictured wing, the same wing blunt side forward, and something in between you start to see what was explored in the 1940s by North American aviation as "laminar flow", attempting to reduce drag by delaying flow separation as much as possible.
Moving the thickest part of the wing back to around 30% and greatest camber to around 40% reduces drag by not only reducing turbulent flow on the top rear of the wing but also adds thrust by tilting the lift vector forward.  The resulting wing has an improved lift to drag ratio but suffers the same issue as the reverse wing: a very sharp, unpredictable stall due to lack of warning buffet and a lower stall AOA from the sharp leading edge.
Rounding the leading edge greatly improves stalling characteristics, leading to the use of slats to have the best of both worlds for cruising or slow flight.
The Kline-Fogelman design even tried removing the rear top portion of the wing, and was studied by NASA (inconclusively), but the time honored way of minimizing drag, as seen in gliders, is as high an aspect ratio as possible, in other words, removing the entire back of the wing.  This is also seen in the more modern 787 airliner wing when compared with the older 707.

Re "the time honored way of minimizing drag, as seen in gliders, is as high an aspect ratio as possible, in other words, removing the entire back of the wing." -- I think you need to elaborate a bit more on that, not following what you mean by "removing the entire back of the wing"!

The next line illustrates well. At a given speed, flow is smoother near the front of the wing.  That, and proportionally reducing the wingtip vortex helps reduce drag.


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Why aren't tilting propellers used as an alternative for ailerons or elevators?
I was wondering what are the reasons for not using tilted propellers fixed to ailerons/elevators/elevons? Or even on wings with no control surfaces at all? Wouldn't the 2nd way of thrust vectoring greatly simplify aircraft design?
There is a huge variety of VTOL aircrafts, but all seem to have puller propellers in frontal wing area with ailerons/elevators separate.

It isn't done because a moving control surfaces is easier to design and build than an engine mount that rotates.
Plus the associated structure needed to accommodate the thrust, p-factor, and gyroscopic loads is going to be a lot heavier than ailerons, spoilers, moving tail plane, etc.
Another issue is if one loses one or both engines, your roll and pitch control disappear as well.

At high flight-speeds, which most modern aircraft fly, propellers are inefficient and noisy, thus quite useless. Supersonic propellers, with propeller tips moving faster than Mach 1 are just a nuisance!
If you plan to rotate the entire engine and motor for instant pitch control you will have huge problems due to inertia and gyroscopic effects. And you'll need a lot of power, that better would be used for other purposes.
The latest way of designing aircraft is without any movable control surfaces at all, to simplify the aircraft as much as possible, and definitely no movable engines or propellers.
A straight wing's center of lift is around 25% from the leading edge, thus all needed infrastructure is forward, while hanging a moveable engine near the trailing edge of the wing needs a lot of infrastructure in that area, adding a lot of weight to the wing. Hanging engines on a wing's leading edge, as the norm is, is just the best solution from many points of view, and even is the best/simplest way of improving the wing's bending manner under load.
If it would be possible all kinds of moveable surfaces (or motors) should be mounted anywhere but on the wing's trailing edge, possibly for the exception of flaps and spoilers. And there you have many swept-wing fighters, that just have control surfaces in the tail (sometimes both the vertical and horizontal tail surfaces do everything: they control roll, pitch, and yaw. and sometimes they are just two, which simplifies things a lot.
The simpler the wing is, the less it costs, and the less it weighs. So preferably, prop-engines are mounted on the fuselage's nose, and preferably as tractors. If you insist on using pushers, you might need very long drive shafts (like those used in the LearFan design), another costly, and often heavy problem item (not much better if you mount the propeller in the nose and have the engine in the rear).
Pusher props are very susceptible to damage, due to dust and stones (and other loose items) being sucked up during power operation. Sadly, well known from the world of Burt Rutan's early designs (and their clones).

In your own example, the wing is slightly swept forward, which means the center of lift is forward of 25% mean wing chord, and as the engines in most cases are the heaviest item in the aircraft, you'd need to mount the passenger cabin and cockpit far forward, like in a Rutan Long-Eze, a popular home-built.
Mounting the engines in front of the wing improves the propeller efficiency, and increases their service life, and often makes less noise, as the air passing through the propeller disc is less disturbed than behind the wing where the air passing over the wing has higher velocity than the air flowing under the wing.
Making the engines movable adds a lot of weight further as there is needed a lot of heavy and expensive machinery to move the engine, and longer fuel hoses, longer cables, longer hydraulic lines, and so on, while a jet engine with a moveable exhaust is complex as well, but very, very, costly, as you need to use exotic materials in the exhaust design, to survive the thermal stress.
Having movable engines/motors are always tricky. The coming tiltrotor-equipped Bell aircraft, that will complement the Osprey, saves a lot of weight by having engines that don't tilt, just the rotors tilt in this new aircraft.

This does not attempt to answer the question as asked by the OP.

Your point #1 is incorrect.  Most modern aircraft do not fly at high speeds.  Commercial jets do, but that is only a subset of aviation.  Plenty of planes fly at (comparatively) low speeds, and use propellors.

Another way to think about it is to think of an airplane's control in flight as a lever centered around the center of lift. One side of the lever will be the weight of the plane, often increased due to the weight of the engine, and the other side is the control surface (usually the tail). For instance, putting downward pressure on the tail will pivot the nose up about the center of lift.
Since you are exerting control with the long lever/arm of the fuselage, it doesn't take much force to effect a change. If you use centrally located engines to do the same work, it will require more power because you lose the help of the "lever"


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What is the width of seat tracks on airliners?
I've been scouring the internet for the track width of seats in airlines, and can't find anything on it. Does anyone know around what that dimension might be?
I'm not looking for the dimensions of the seats themselves, but the width of the tracks that the seats attach to.

Hello lulubelle, welcome to Aviation.SE!

There is an entire chapter for the seats in this book: Aircraft Interior Comfort and Design


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How do exhaust cones affect the performance of turbine engines?

I've seen explanations stating that it creates uniform stream of exhaust gas towards the exhaust duct, however without the cone wouldn't it still be considered a uniform stream?
Also since a divergent duct is formed between the outer duct, and the exhaust cone, does that slow the air down so it reduces turbulence?


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How does a gyro compass indicate true heading?
From what I've researched, a gyro compass is usually calibrated with with reference to a magnetic compass. Once you've engaged the gimbal locks, and start to rotate the compass to a magnetic heading; will it automatically compensate for true heading or will you not even reference a magnetic compass when calibrating?
Or are there cards used to indicate what's your position from true north, based on your magnetic indication?

The directional gyro (DG) does not know about heading. Its gyroscope will hold its position (e.g. the heading you set from the magnetic compass) in space. The plane is turning "around it", but DG is holding its position, so you can read the heading from the scale fixed to the airplane while the gyroscope holds its position in space. Only friction and other forces (acceleration forced upon the aircraft) force the gyroscope to wander from its position.
E.g. the gyro shows a magnetic heading if set using a magnetic compass and it shows a true heading if set using a GPS (or some map feature like a road with a heading visible on a map).

A gyro compass utilizes physical forces, including the procession of the earth to determine direction.  This provides a more useful north than a magnetic compass for navigational purposes.
A directional gyro can be slaved to a compass, but it is distinctly different from a gyro compass.
To be clear, a gyro compass does not use magnetic forces, and therefore is useful on boats where a steel structure might influence a magnetic based reading.  https://en.wikipedia.org/wiki/Gyrocompass

Aircraft are too fast for the auto-alignment of gyrocompass to work, so they don't have them. Inertial navigation systems do use the auto-alignment when powered up at the gate for initialization though (which is why it usually takes a couple of minutes).


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What's the difference between FMS and FMC?
What's the difference between FMS (Flight management System), and FMC (Flight management computer)?
Can the flight management computer be thought of as what's manipulating the input information from the performance/navigation databases, and the FMS as being what actually provides the information?
I understand the information that's involved with the system, I'm just trying to define the difference based off an analogy of sorts.


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Partial Serial numbers on Military Aircraft - what combination is unique?
Modern US military aircraft have partial serial numbers painted on their tails. Interestingly, it seems these serial numbers are actually not quite enough to be unique on their own, being comprised of only the year the aircraft was ordered, followed by the last 3 digits (usually) of the serial number. On occasionally this is not a unique combination by itself. Is there a specific combination of tail markings that is guaranteed to be unique? For example, if one combines the branch markings (such as 'AF' for Air Force) and/or the base code (such as 'AZ' for Arizona National Guard), would that be guaranteed to be unique?
Thanks so much for any insight.

Welcome! I'm not sure I understand your question... are you trying to find a way to improve the marking system of the US army?

@mins I don't think he's trying to propose anything. I think he's just trying to figure out how the military deals with the fact that the system can allow two aircraft to have the same markings.

Related: http://aviation.stackexchange.com/questions/24895/how-to-understand-us-military-aircraft-designation-on-the-vertical-stabilizer/24897#24897

Every combination of painted tail number + aircraft type should be unique. I don't really have proof for it, but because of the number sequencing, duplicates can only occur between aircraft that are so far apart, that they should be easy to distinguish. Feel free to correct me on this, though:)
Paint and markings always can change when an aircraft moves to another unit.

@Jordy, when you say different aircraft type could be used to differentiate, do you mean different models, or entirely different categories, such as fixed-wing vs. helicopter? Thanks.

I meant different models. Aircraft with the same 'first digit' of their tail code should be at least ten years apart. I'm not sure about older (pre 1960) aircraft, but at least F-15, F-16 and C-130 have two digits of the FY on their tail, which makes it impossible to have a duplicate for the next 100 years. C-5 and C-17 only have the last digit of the FY, but all their tail codes seem to be different. I think there is some kind of mechanism in place that prevents double codes from happening. http://www.planespotters.net/production-list/Boeing/C-17 has some examples, but it's not very clear

I can only address the AF system, but I assume the other services systems are similar.  The AF serial numbers for vehicles (the system applies to all vehicles including ground vehicles) are made up of the letters "AF" followed by the contracted delivery year (2 digits) followed by a sequential number that restarts at 1 every year.  The pic below is of an F-22 assigned to the 1st Fighter Wing (the FF code).

So this aircraft was purchased in 2008. The sequence number is 161, and would have been assigned from a block of numbers provided in the contract.  The contracting officer was given the block by the office that keeps the master list.
It's worth noting that the paperwork and the data plate is where it has to be complete. What's painted on the a/c is just used for the convenience of the crews. For some a/c such as KC-135's and B-52's whose production run was less than 10 years, they often just us the last digit of the year and the sequence number.  Most of the tankers I see have a 5 digit number that starts with 2, for 1962.
In a fighter squadron, most 'local' documentation just refers to the last 3 digits.  example: 061 and 813 were how we referenced two of the F-16s in the test squadron.

If I remember correctly, military aircraft do not identify themselves by those painted serial numbers in radio communication. Combine that with the odds of a squadron having two a/c of the same make/model 1,000 serial numbers apart, and the reality is that this is a non-issue.

I just checked some of my old photos. In 1979 when I was working in a SAR squadron at MCAS Cherry Point the birds used the full BuNo as tail number. But we were different, the call sign of the active bird was always "Pedro". We had a total of 3 birds and they were rotated on the duty.

Each service uses its own method.
There's a nice summary of how serial numbers are assigned to military aircraft here.
The US Army began in 1991 to use year/sequence number.  Example:
92-00518 Bell-Textron OH-58D(I) Kiowa Warrior delivered in 1991.
The US Navy uses two numbers to identify the aircraft: the Bureau Number, and the side number/call sign.
The bureau number is typically a six digit number that remains with the aircraft/airframe for its entire life, and is assigned once it has been delivered to the government.  A given Bureau Number may have different side numbers painted on it, depending upon which squadron it is assigned to.
For example:
An SH-60B Seahawk assigned the bureau number 1613xx would have a two digit side number, typically painted on the forward fuselage just below the door on both sides ... if it was assigned to a West Coast squadron. "Tactical Call Sign Lonewolf 45"
If it were assigned to an East Coast Squadron,  it would have a three digit side number. (Tactical call sign "Proud Warrior 430")


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What is the dimensionally smallest 2-seat helicopter?
Considering only a two place helicopters (2 crew, or 1 crew and 1 passenger).

Which dimension are you looking for? Length over all, rotor diameter, cabin width, fuselage length, height or weight?

Thank you for your question! Sum of LOA, rotor diameter and height. Imagine some cubes. Of all 2-seat heli's which could be contained inside smallest cube?

See: List of ultralight helicopters

My vote would be for the RotorWay Scorpion II.  Tiny little things would fit in a living room!


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Putting the yoke behind your elbows
In the 1989 documentary film "Always", our protagonist pulls out of a high-speed dive by reaching around the yoke and pulling with the back of her arms:

Is this unusual, for a large high-speed aircraft (a B-26 adapted for firefighting) without powered flight controls?

I could see where this would involve getting your torso involved in pulling on the yoke, instead of just your arms possibly giving you more strength for the pull, however, you would not be able to do this if you were properly strapped in with a shoulder harness as there wouldn't be enough room to move like that. I note that there is no shoulder harness in the screen grabs you provided, nor do I know if the B-26 (or firefighting adaptations) had them. However, I wouldn't count on a TV show/movie (even if a documentary) to be completely correct.

I did note that no-one in the entire film is wearing a shoulder harness. Lap belts only throughout.

That's Holly Hunter, and the film is not a documentary.  FWIW...

It's a documentary film about the early life of Elastigirl from The Incredibles, Michael, this is uncontroversial ;)

Technically, you could get a harder pull by removing your forearm muscles from the situation, having the weakest muscles, and pulling mostly with your shoulders and back alone.
I have a set of straps used for moving furniture that hook into your arms right at the elbows, and achieve the same effect by removing the load from your forearms as you lift (you brace your hands on the piece with your elbows at 90 degrees), putting all the load on your shoulders, back hips etc.  You can lift heavier pieces than otherwise.
Problem is, you have the elevator trim system, and for the airplane to go into a dive, you have to have it trimmed to a very high speed (Nose Down), or the tab on the elevator has maybe fallen off, or maybe the autopilot trim system ran away Nose Down.
If it's just trimmed wrong, that is, trimmed for high speed (excessive Nose Down) which is making the airplane dive to achieve its trimmed speed, you would just wind the trim wheel to a lower speed setting (Nose Up) and let the tab do the work.
If the tab has fallen off, or the trim mechanism that moves it is jammed or broken with the setting at a high (Nose Down) speed, you could use that technique to pull the nose up and overpower the trim system, but the need to hold that force wouldn't go away once you are level - you'd have to maintain that pressure all the way until the landing, and you'd be pretty tired, and now you can't use the ailerons as well with your arms hooked like that, so you are in a bit of a pickle if you are by yourself.
So the main thing is, you can theoretically make an airplane with a trimmable elevator do that, with the need to apply high forces to pull the nose up, say because the trim system is broken, but once the nose is level, you are still stuck with that trim state and won't be able to let go.  If the trim is still working, you would wind the trim wheel to take away the pressure, and if that was the case, you could've used that feature right at the start.
Your trim condition wouldn't magically return to normal just from the act of getting the nose back to level, without retrimming for your level flight trim speed.  The movie presents an old movie cliché for drama purposes, of the "spontaneous high speed dive" which automatically resolves when you pull out, which isn't how airplanes really work.
A more likely scenario in the real world would be where the airplane departs into a stall/spin and finds itself in a dive as a result, but in that case it'll be trimmed for a low speed and it won't take that kind of pitch force to recover from the dive, as the airplane will be naturally trying to raise its nose on its own.  You won't need all of your strength to pull, and the main challenge will be trying to respect the maximum speed limit of the aircraft while not exceeding G limits from the pull (you pull, but not too hard).  When pilots doing aerobatics, fall out of maneuvers and end up in dives, the challenge is not finding the strength to pull, but modulating the force of the pull to stay within both G limits and speed limits.

It's not about removing the forearms from lifting, those straps allow a more direct transfer of weight to your legs. This scenario is a not trying to lift, but to pull.

Lift, pull, it's still the same concept - relieve the forearms and hands from the need to take part in applying and sustaining the heavy force, whatever the direction.

Did the B-26 have MCAS? :D

I was thinking that myself!  Conair in Canada used to operate a large fleet of B-26s and for a long time that was my ultimate dream job.  They eventually switched them out for Grumman Trackers, and turboprop-ized those with an in-house STC, the Firecat.

Try rowing without using your arms @JohnK.


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How do we get Required RVR or Actual RVR for an instrument approach?
When executing an instrument approach, when the pilot should start reference the RVR reported. Also, How do we get the required RVR for the current approach in execution and actual RVR. I think actual RVR can be part of METAR data. But I am not sure on the required RVR.


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why are airplane propellers always undersized?
While calculating propeller static thrust by using a famous Prop-power-calculator.xls (by Pé Reivers),
I've noticed that no matter what "stock" configuration I put into the calculator, I do always get the propeller power required half or third of the engine power available.
I.e.:

Zivko Edge 540: Lycoming AEIO-540-EXP 300HP@2700rpm engine, HARTZELL
76" prop @ 11.5" pitch
Calculator given performance: 51HP, 154Kg thrust
Piper Sport: Rotax 912ULS 100HP@2400rpm engine, Woodcompo 67" prop @
10" pitch
Calculator given performance: 17HP, 88Kg thrust

!NOTE - calculator is for 2-blade props, while above planes have 3-blade props. However, that doesn't change the mismaching in numbers a lot.
Above engine RPM's are with reduction applied (i.e. 1:2.43). That means the actual HP available is two-fold!.
I would imagine everything shouldbe the other-way around(?)

Reduction rates of 1:0.5, RPM's * 2, engine power / 2
Or propeller driven directly by the shaft
Or prop diameter increased (not to practical perhaps)
Or pitch inreased
Or number of blades increased?
Or all of above?

What am I missing here?

300hp = 223,710 watts, where did you get 38,216 from? It should also be noted that the worksheet you are using is meant for use on R/C airplanes...

Another possible explanation is that the engine are less effective with altitude, so the power at sea level may be greater than the power at the ceiling altitude.

Ron, that's exactly my point. Particular prop @ particular pitch @ particular RPM gives that much of a static thrust. Why are the engines scaled up if prop is technically unable to push for more?
I dare to disagree that the math behind the static thrust calculation differs for RC or True airplanes.

I'm not talking about thrust, at the point you enter the engine power in watts, you are off by a factor of almost 6. Edit: Ok, I see you can't enter the engine power there, but where do you enter engine details at all? I can't find that.

This site calculates the 11.5 inch pitch, 2800 RPM, 300hp engine combo to deliver about 3690lbs of thrust, which is much more realistic.

@RonBeyer - the Zivko Edge 540 weighs 1,170 lbs.  A thrust to weight ratio of over 3:1 seems unlikely. Am I missing something?

@DanPichelman I'm not sure, possibly. I can't find a reliable source for the formula's to verify. The Edge 540 has a power:weight ratio of .21hp/lb. So if the propeller can generate 3lbs of thrust with .21hp, then it is realistic...

@DanPichelman, the problem is that for propeller, the engine provides (roughly) constant power, and power is thrust times speed. So statically, perhaps. At any reasonable speed, definitely not (it could provide 1 lbf around 50 knots, which is about right as the plane can climb vertically).

Anyway, if it is for R/C airplanes, there are likely some experimental factors that are simply way too different from corresponding values at full-scale.